An annular groove is worked into the wall of the cylinder housing adjacent its one end in conventional arrangements of this type, into which annular groove is inserted for example a slotted clamping ring. During a guiding of the cylinder end cap against the screw collar ring, the cylinder end cap abuts the edge of the one end of the cylinder housing, while the screw collar ring rests on the clamping ring.
Due to the annular groove which receives the clamping ring, the cylinder housing must have a substantially thicker wall than is necessary with respect to strength requirements concerning the medium pressures occurring inside of the cylinder housing. Thus the conventional arrangement uses much material and is relatively expensive to manufature. The expense is additionally particularly increased by the clamping ring being a separate part. Furthermore relatively heavy cylinder housings are obtained due to the great wall thickness. Finally, the massive construction of the cylinder housing wall has the disadvantage that for reasons of cost, often no corrosion-resistant material is used, so that the known arrangements are not suited for use for example in the food industry, the chemical industry, the drink industry or in electroplating.
Similar disadvantages exist also in a different type of connection between the cylinder housing and the cylinder end cap, in which the cylinder end cap is screwed into the front end of the cylinder housing. Here too it is necessary because of the arrangement of the thread on the cylinder housing to make the wall thickness of the housing greater than is necessary for the inside pressure.
Therefore the basic purpose of the present invention is to provide a piston-cylinder unit of the above-mentioned type which does not have the mentioned disadvantage and in which the wall thickness of the cylinder housing can be measured according to the occurring inner pressures, without interferring with the stability of the connection.
This purpose is inventively attained by the front end of the cylinder housing being bent radially outwardly and the radially bent flange forming with its axially facing front surface a stop surface and with its axially facing rear surface the contact surface.
In this manner, a separate clamping ring is not needed, the function of which is taken over by the radial flange. Together with the clamping ring the arrangement of an annular groove is also not needed, so that the wall thickness is not influenced by the connection. All in all, a simpler and less expensive arrangement is thus obtained, which has few parts, a light weight and can be produced with a minimum of material input. The latter permits a manufacture of corrosion-resistant material for example of V2A-steel, without effecting an excessive increase in price of the manufacture. A further advantage can be seen in the radial flange forming both the stop surface for the cylinder end cap and also the contact surface for the screw collar ring, so that during a guiding of the end cap, the applied clamping force and the counterforce which is directed opposite thereto act onto the same cylinder housing area, namely onto the radial flange. The radial flange is, so to speak, clamped between the cylinder end cap and the screw collar ring. Compared with this in the conventional arrangement, a torque is applied onto the clamping ring, because the contact surface is arranged radially offset with respect to the front edge of the cylinder housing, which serves as a stop surface, which can result in deformations.
In principle, it is possible for the radial flange to be bent also radially inwardly. In order not to unnecessarily reduce the inside of the cylinder housing and to influence the piston stroke, it is, however, advantageous that the radial flange be bent outwardly in radial direction.
The radial flange is manufactured advantageously by axial compression, pressing or flanging, for example wobble flanging.
In an embodiment, which is particularly preferable with respect to stability, it is provided that the radial flange contains an axially frontwardly facing bent portion which forms the stop surface and a rearwardly facing bent portion which extends parallel to the front facing portion, is opposite same and forms the contact surface, which bent portion is separated from the outer bent portion by a 180.degree.-bead. The free end of the bent radial flange is preferably formed by the rearwardly facing bent section.